1. Field of the Invention
Embodiments of the present invention relate generally to new combinations of materials comprising compounds known to produce light radiation when subjected to mechanical energy and various castable, polymeric (e.g., silicone, urethane, and epoxy) elastomers. These embodiments further relate to providing articles made with materials comprising castable elastomer compounds combined with materials that produce light in response to absorbing mechanical energy. In addition, a specific embodiment of the invention may relate to articles, such as toys, that emit light when struck.
It is known that all bodies radiate electromagnetic energy, so-called black body radiation or thermal emission. xe2x80x9cHotxe2x80x9d bodies that are self-luminous solely because of their high temperature, therefore, represent a special case and are said to emit visible light by incandescent radiation. All other forms of light emission are said to be luminescent, a process that involves 1.) absorption of energy; 2.) excitation; and 3.) emission of energy, usually in the form of radiation in the visible part of the spectrum. Therefore, some source of energy is required in order to trigger and/or to continue light emission since such emissions represent a net loss of energy by the body. Most of these kinds of luminescence are classified according to the source from which this energy is derived, e.g., the light from a gas discharge lamp, produced by the passage of an electric current through the ionized gas is said to be electroluminescent.
In particular, light which results from energy supplied to a material in the form of mechanical energy, is known as triboluminescence; also referred to as mechano-luminescence or fracto-luminescence. The effect is thought to arise through fracture or cleavage of individual crystals of a certain class of solid materials together with a concomitant electrical breakdown. However, the effect is poorly understood and may be the result of any input of mechanical energy which provides frictional force, or some amount of strain energy, to a particle of the identified class of materials, even of non-crystalline materials. Furthermore, the effect may arise also as the result of an electric charge separation as new interfacial surfaces are created as the material is either cleaved or breaks free and separates from a surrounding host matrix in which the material is embedded. In either case, it is known that when mechanical energy is imparted to certain compounds these compounds emit light energy and that this effect is intense enough in certain materials to be easily detectable. The observed range of light wavelengths runs from red to deep ultraviolet.
Under certain circumstances, an indicating sensor providing a pulse of detectable light would be a useful method for verifying whether or not various internal system functions have activated, or whether or not certain parameters in the internal system environments had been exceeded. Events such as movement of mechanical actuators, pistons, or gears, the activation of an explosive actuator, acceleration loads beyond a predetermined level, such as impact events (e.g., air bag deployment), and acoustic noise and the like, are examples of events to which a shock-sensitive indicator device could be applied.
Additionally, objects such as a child""s ball may provide enhanced interest value if that object provides a form of reinforcement stimulation through the effective use of a light pulse as the object is bounced or otherwise engaged with in play. Until now, it has been believed that the physical action of the ball was sufficient to capture a child""s attention. However, with young children, after a low number of repetitions bouncing a ball becomes tedious, resulting in a dissipation of interest. Accordingly, a toy ball which provides an optical stimulus would have increased play value. (There are balls that flash but these require a source of power such as a battery.)
2. The Prior Art
Resilient, flexible, and translucent elastic materials necessary for producing cast-to-shape objects, including seals, indicators and toys are well known in the art. Examples are U.S. Pat. Nos. 2,504,388, 2,999,077 and 3,674,420 to Braley, Nitzsche, et al., and Fulton, et al., respectively, all describe various room-temperature vulcanizing (xe2x80x9cRTVxe2x80x9d) polysiloxane compositions, while U.S. Pat. Nos. 2,830,038 and 3,158,586 to Pattison and Krauss, respectively, describe compositions for preparing polyurethanes. Furthermore, triboluminescence is also a well-known phenomenon. However, the application of triboluminescent materials to physical sensors is some-what limited. Examples are U.S. Pat. No. 4,020,765 to Glass, et al., that describes a munitions fuse relying upon a light signal generated by ordnance of a triboluminescent material coating the inside of the ordnance nosecone as the ordnance strikes a target; U.S. Pat. No. 5,905,260 to Sage, et al., which describes a sensor for detecting damage in aircraft structures by connecting a piece of light guiding optical fiber with a triboluminescent material; and U.S. Pat. No. 6,270,117 to Storey which describes a sensor utilizing a moving bar of quartz to generate a light flash which is sensed and actuates a vehicle air bag. None of these patents, however, describe a sensor or a toy comprising a triboluminescent material dispersed within an elastic media material, although prior U.S. application Ser. No. 09/792,670, herein incorporated by reference, discloses a light emitting device in which triboluminescent particles are dispersed throughout a low density, frangible foam body. While this device works well, it has the disadvantage of being capable of single use only. What is needed is a multi-use device.
Light produced from a triboluminescent event may be useful where there is a need to record the response to a mechanical event without the need for relying upon a source of electrical power, or where there is a desire to provide an object that emits light when struck.
A principal object of the present invention is to provide systems and devices incorporating triboluminescent constituents for providing a transient source of light emission.
Another object of this invention is to provide a device for generating a source of light emission that is subsequently converted into an electrical signal.
A further object of this invention is to provide means for containing one or more triboluminescent constituent materials and means for suspending said materials in a solid, or semi-solid elastomeric media.
Another object of this invention is to provide a flexible, transparent or translucent, solid or hollow body for containing particles of one or more triboluminescent materials dispersed throughout the flexible body.
These and other objects and advantages of the invention will become apparent and will be more fully set forth as the description thereof proceeds in the following specification and claims considered in connection with the attached drawings to which they relate.